I took the train from Paddington to Hay on Thursday. The train is completely packed, with some people standing. I'm impressed that there is so much interest in the festival. At Slough and Reading, however, they all get out and I'm almost alone in the carriage the rest of the way. I suppose that people are converging upon Hay from all directions, since thousands are expected, but how are those from London getting there? Are they all going by car?

If so, they are out of tune with one of the main themes of the event. Sessions about climate change, energy security and sustainability brook large, as indeed they should. I'm there to talk about my new book The Politics of Climate Change, which I'm discussing in a panel, two speeches and five or six interviews and podcasts over the course of some 24 hours. The panel, organised in conjunction with Unesco, is part of a series of public debates labelled Earth, Fire, Wind and Water. I'm talking about fire – ie, energy. There ensues a good and spirited exchange of opinions with the other panellists and with the audience. One panel member is David Mackay, author of Sustainable Energy – Without the Hot Air. It's a tour de force, which takes the reader through the minefield of claims and counter-claims about renewable technologies, disposing of much of the hype about them along the way. In the discussion he is forceful and convincing, but has a pleasing style of whimsical humour too – much the same mix as he offers in his book in fact.

The next morning I take part in the launch of the Welsh Assembly's sustainable development strategy, somewhat quaintly labelled One Wales, One World. Why should the rest of the world, which is a very big place, take any notice of what happens in a tiny nation like Wales? Having heard politicians in many countries purveying exaggerated claims about what they can achieve, this was a refreshing change.

The first minister, Rhodri Morgan, speaks first. He's a hoot – politician as stand-up comedian. Most of the answers he makes to questions are prefaced by a joke. The effect is to charm the questioner, but also allows Rhodri time to think carefully before formulating his replies. Behind the throwaway style his comments are actually acute and insightful. Jane Davidson, the environment, sustainability and housing minister, speaks next, saying that sustainability will be an "organising principle" of all branches of Welsh government and providing plenty of concrete examples of innovation to bolster her case.

In the afternoon I gave a lecture about my book and respond to questions from the floor.In December this year some 200 nations will meet in Copenhagen to try to reach global agreements about how to contain climate change. I support these endeavours whole-heartedly, but I have doubts; it is hard to get such a large number of nations all to agree about anything. Moreover, there are few if any sanctioning mechanisms that can enforce targets for greenhouse gas emissions reductions might be established. Only a small handful of countries look likely to meet the targets set at Kyoto several years ago – and those targets were in any case far too low in relation to what will be needed effectively to contain climate change.

Whatever happens at Copenhagen, it is the developed countries that will have to take the lead in radically starting to cut back on their emissions. If they can't show they mean business, the large developing countries, China, India and Brazil, aren't going to do much if anything. China has recently overtaken the United States as the world's largest emitter of greenhouse gases, measured in an absolute sense. In terms of emissions per person, however, it is far behind the US; moreover, the industrial countries historically have been responsible for the vast bulk of the greenhouse gases.

At Hay, as in my book, I argued that the key issue in climate change politics within the industrial countries is to bring the issues into the mainstream. The vast majority of the public, in virtually all such countries, express worries about climate change, but for the most part it does not touch their everyday lives at all. We have to deal with what I call Giddens' paradox. Climate change is about avoiding or minimising abstract, largely future, risk. It is not visible in people's everyday lives and most simply filter it out from their day-to-day concerns. The paradox lies in the fact that if we wait until it does becomes visible - in the shape of disasters that can be unequivocally attributed to climate change - it will by definition be too late to control it. Once they are in the atmosphere, most greenhouse gases stay there for centuries and at the moment at least we know of no way of getting them out.

After that, it's back to London. The train is full. Is everyone, like me, leaving already? If they are, I think, I hope they got as much from my short visit as I did. Well, no, again it's a different constituency. There must be something about Reading and Slough. Most people get off at those stops and the train continues onto London largely empty. I leave the reader free to ponder the metaphor.